The present invention relates to a detection probe for use with a detecting unit in the sector of analytic devices and scanning type tunnel microscopes.
One typical arrangement of a scanning type tunnel microscope is that a tunnel current flowing in between a sample surface and a tip of a detection probe is detected, and atomic structures are observed by effecting control between the sample surface and the tip of the detection probe so that the tunnel current becomes constant. In the thus arranged microscope, the resolving power is determined by a condition of the probe tip, and it is therefore required that the probe be shaped more acutely to increase the resolving power.
Known conventional methods are that a tip of a rod formed of platinum or tungsten is sharpened in a conical shape by mechanical grinding, or the tip is shaped by electrolytic grinding (Japanese Patent Laid-Open No. 61-332326 discloses a method of forming a needle-like member by the electrolytic grinding).
There are caused drawbacks incidental to the probes manufactured by the foregoing conventional methods. The mechanical grinding does not provide a smoothly stretched probe tip but creates sagging, as a result of which a sharpened tip is not obtained, or a wire diameter is limited because of creation of grinding undercuts when applying a grindstone in the case of a small wire diameter. Based on the electrolytic grinding, it is in contrast advantageous that a reaction time can be reduced when the wire diameter is small rather than large. If a timing at which to stop the reaction deviates, this results in such a defect that the acute tip can not be attained. Besides, the tip of the probe manufactured by the mechanical grinding or electrolytic grinding tends to be destroyed simply by bringing the probe into slight contact with the sample surface on the occasion of effecting a rough locating process on the sample surface during a scan of a scanning type tunnel microscope. If a well-conditioned rough locating mechanism is not prepared, there arises a problem in which the probe has to be often replaced.